It is known that robots or manipulators are used in industrial applications such as the assembly of workpieces to a final product, the packaging of small objects or the grading of small objects. A robot can include several degrees of freedom in movement, for example three or six, but also manipulators with only two degrees of freedom or with seven and more degrees of freedom in movement. Each robot can be controlled, for example, by a dedicated robot controller.
A robot with three degrees of freedom in movement, for example, may have the ability to move an interface platform on the tip of the robot arm in three geometrical dimensions within its working range. For some applications a gripper tool is mounted on the interface platform. This type of robot can be suitable for so called pick and place applications whereas the robot is arranged, for example, over a conveyor belt transporting a plurality of individual small objects to be picked from the conveyor belt and to be packaged afterwards. Those robots may have a working range of, for example, +/−50 cm in each dimension whereas several and parallel working robots can be arranged along the conveyor belt. A similar application is, for example, disclosed in U.S. Pat. No. 6,328,523.
Of course, robots with six or seven degrees of freedom in movement are also suitable for such applications. But those robots are bigger and have a working range of for example 3 m around their rotary base. A known application for those robots is for example the assembly of car bodies in the automotive industry.
These robot applications can include for their control, but also due to safety aspects, a sensor based feedback from their working environment, where a plurality of different suitable sensor types is known. The feedback signal could be for example based on a light barrier around the robot which covers some security aspects to prevent incidents with personnel. But also cameras are known sensors for generating a feedback signal, especially for pick and place applications. In this case the stationary cameras observe the small objects moving along on the conveyor belt. The pictures from the camera can be analyzed permanently concerning the number, type and position of the small objects on the moving conveyor belt. Based on this analysis, the robots pick selected objects from the conveyor belt and place them for example in a package to which they belong. A robot system having an image processing function is disclosed for example in U.S. Pat. No. 7,177,459.
Such an analysis can be performed by a dedicated processing unit connected to the sensors, which analyzes all measurement signals. The effort of analyzing those data is strongly dependent on the kind and density of the objects on the conveyor, so the analyzing effort for one sensor may be at one time significantly higher than for another sensor and some time later significantly lower. Some data may have to be analyzed in real-time, such as security relevant data within not more than a few ms. Other data are less time critical and can involve for example an analysis only within a few 100 ms or some seconds.
Known processing units might become a bottleneck for the whole process in the case where an unexpected high amount of data has to be analyzed at the same time, so that the analysis of some data might be delayed and can not be considered in the robot control. In an exemplary worst case, the production process has to be temporarily stopped.